Afog that develops when warm, moist air blows over a cold current (such as the california current) is an example of fog.

The correct answer is- advection

Explanation:

Advection fog is also known as sea fog which is produced when warm and moist air is flowing over colder water. Normally it is seen in spring and winter when the seawater is cool and the rising sun produces saturated air by warming the moisture saturated the winter land.  

So when this moist and warm air moves and blows over the cold water current it forms advection fog. So advection fog can be seen in those areas where cold water is upwelling like in California coast or where moist air encounters cold water.

the correct choice is i and iv.